1. Field of the Invention
This invention relates generally to mechanical refrigeration systems, and particularly to mechanisms for purging the refrigerant of said systems of foreign liquid impurities such as water.
2. Description of the Prior Art
In refrigeration systems comprising a compressor, a condenser, a refrigerant expansion device, and an evaporator, a major problem is the purging of condensible and non-condensible foreign contaminants. Of primary importance is the removal of excessive moisture introduced into the refrigeration system through leaking seals, faulty piping, introduction of moisture laden refrigerant fluid or lubricant, moisture on new parts installed in the system, condenser leaks, and evaporator leaks. It is well known that moisture accumulating in a refrigeration system adversely effects operations by causing corrosion, buildup of oil sludge, and freezing of the refrigerant expansion device.
As taught in U.S. Pat. Nos. 3,410,106, 3,145,544 and 3,013,404, purge mechanisms may be constructed utilizing a separate chamber wherein cold refrigerant is used to condense moisture drawn from the headspace of the condenser unit. As refrigerant vapors are also condensed in said purge units, piping and float valves are necessary to separate liquid refrigerant from the water to be drained. Due to the expense and mechanical limitations of said purge mechanisms, their use is primarily confined to refrigeration equipment in capacities upwards of 50 tons.
Also known to the prior art are electrostatic precipitator purge mechanisms as taught by U.S. Pat. No. 2,691,280. Use of this type of purge unit has not found wide acceptance in refrigeration systems of less than 50 tons capacity as a result of high operating costs and relatively high initial costs.
The typical dehydrator presently in use in most refrigeration systems, and, in particular, systems of relatively small capacity, is the chemical type, typically containing silica gel and activated alumina. These chemical drying agents are contained within a body suitably adapted to removably connect within a refrigerant conduit of the refrigeration system such that they may be replaced when exhausted due to adsorption of the maximum amount of moisture. While economical to install, said chemical dehydrators, as a result of their disposable design, increase maintenance expense and involve loss of refrigerant when removed for renewal.
The final purge device known in the prior art comprises a trap installed in a low leg of the piping of a refrigeration system. This trap-type purge device is adaptable to systems utilizing a refrigerant of low density such as ether or air as taught in U.S. Pat. Nos. 240,830 and 258,682. Water, being heavier than such refrigerants, will be separated by gravity and will accumulate in the trap from whence it may be drained. With the advent and use of more efficient refrigerants such as Freon 12, Freon 22, and methyl chloride, said trap-type purge devices are no longer operable; modern refrigerants, being heavier in their liquid state than water, would drain from such traps prior to the accumulated water.